Epigenetics: The UltimateMystery of Inheritance

Richard C. Francis

For more than 10 years, scientists
have known nearly every letter in the
human genetic instruction book. But
perhaps more interesting than those
letters are the doodles in the margins
and the highlighted passages — chemical modifications to DNA and its associated proteins known as epigenetic
marks. These scribbles may actually
control how genes function, and thus
how a person looks and acts. And these
changes are passed along to future
generations, like carbon copy overlays
in new editions.

Researchers are only beginning
to decipher this cryptic language,
but already it’s clear that whatever
these graffiti have to say is going to be
important. Such epigenetic modification may be at the root of many diseases, for example. Epigenetics links
external experiences to the molecular
machinery inside cells. Francis’ book is

Rambunctious Garden

Emma Marris

What does it mean to be wild, and canhumans restore wildness to a planetthey’ve spent their history trying totame? Marris hauls out a wheelbarrow-load of research indicating thathumans have altered nearly every inchof the terrestrial landscape at one timeor another (even ignoring the globaltransport of air pollutants and pertur-bation of the climate). So any claimthat a place is “pristine,” she argues,Marris recountsefforts under way across the globe to“rewild” various sites to conditionsthat existed a century — if not 10 mil-lennia — ago. Such projects invariably

intended as a guided tour of this mysterious new landscape.

Each chapter starts with an enter-taining or intriguing example of howepigenetics affects human and animalbiology and inheritance. It’s not oftenyou find José Canseco, mouse moth-ers, Dutch faminevictims, sea urchins,identical twins andTasmanian devilsall in the same book,but you will here.Francis just man-ages to save his storyfrom crossing intotextbook territory by weaving theseexamples throughout the chapters.

It’s still early days for the science of
epigenetics, and researchers keep discovering layer after layer of epigenetic
wallpaper plastered over DNA. Francis
hits the highlights here, but stay tuned
for more installments in this fascinating new science. —Tina Hesman Saey

W. W. Norton & Co., 2011, 234 p., $25.95

require compromises. Once-keystone
species may no longer walk or slither
across the planet. Budgets may not
stretch to do more than a partial job.
Unurbanized spaces may be too small
to support big carnivores.

If no place is pristine, determining
what should be restored ultimately
becomes a judgment call. So does
determining the benchmarks biologists
might use to measure success.

None of these constraints argue for
throwing in the towel, or trowel, Marris
says. She points to regions where allowing small areas along roads or farms to
go untended has brought back species
that people had assumed were gone
for good. She invites readers to turn
the idea of what constitutes smart gardening on its head. One example: Tiny
patches of the urban landscape — like
yards — could be encouraged (with a
little help) to evolve into novel, yet
sustainable, marriages of native and
not-so-native species. —Janet Raloff